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101.
Although invertebrate drift is an important ecological process in lotic ecosystems, very little is known about it in Kenyan rivers. The primary aim of this study was to investigate the effect of driftnet mesh size and exposure duration on drift density in 2017. Drift samples were dominated by Chironomidae, Baetidae, Simuliidae, Caenidae and Culicidae. The 100 µm mesh driftnet had the highest mean invertebrate density, followed by the 250 µm and 500 µm nets. Invertebrate drift densities decreased with increased exposure time. This study demonstrates that sampler mesh size and exposure time should be taken into account when characterising invertebrate drift in streams. Future studies should consider sampling different biotopes and during different seasons. 相似文献
102.
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104.
Relapsing polychondritis (RP) is an autoimmune disease that affects extra-articular cartilage. Matrilin-1-induced relapsing
polychondritis (MIRP) is a model for RP and is useful for studies of the pathogenic mechanisms in this disease. There are
indications that the major histocompatibility complex (MHC) class II plays a major role in RP, since DR4+ patients are more commonly affected than controls. We have now addressed the role of the MHC region, as well as the non-MHC
contribution, using congenic mouse strains. Of the MHC congenic strains, B10.Q (H2
q
) was the most susceptible, the B10.P (H2
p
) and B10.R (H2
r
) strains developed mild disease, while B10 strains carrying the v, b, f, or u H2 haplotypes were resistant. A slight variation
of susceptibility of H2
q
strains (B10.Q> C3H.Q> DBA/1) was observed and the (B10.Q × DBA/1)F1 was the most susceptible of all strains. Furthermore, macrophages and CD4+ T cells were the most prominent cell types in inflammatory infiltrates of the tracheal cartilage. Macrophages are the major
source of many cytokines, such as interleukin-10 (IL-10), which is currently being tested as a therapeutic agent in several
autoimmune diseases. We therefore investigated B10.Q mice devoid of IL-10 through gene deletion and found that they developed
a significantly more severe disease, with an earlier onset, than their heterozygous littermates. In conclusion, MHC genes,
as well as non-MHC genes, are important for MIRP induction, and IL-10 plays a major suppressive role in cartilage inflammation
of the respiratory tract. 相似文献
105.
Members of the ZFY and ZNF6 gene families have been cloned from species
representing different taxa and different modes of sex determination.
Comparisons of these genes show the ZFY-like and ZNF6 sequences to be
strongly conserved across marsupials, birds, and lepidosaurians. Sequence
analyzed by neighbor-joining indicated that both gene families are
monophyletic with a high bootstrap value. Pairing of sequences from males
and females of nonmammalian species showed there to be no significant
difference between male and female sequences from a single species,
consistent with autosomal locations. The molecular distances between murine
Zfy-1, Zfy-2, and other ZFY-like sequences suggested that Zfy genes have
undergone a period of rapid evolutionary change not seen in human ZFY.
相似文献
106.
Transposable elements induce spontaneous mutations, promote genome
rearrangements, regulate gene expression, and participate in the horizontal
spread of genes encoding traits such as antibiotic resistance among
bacterial genera too distantly related to undergo homologous recombination.
Here we review the bacterial transposon Tn5 and focus on those aspects of
its functional organization and transposition which provide insights into
how it and other elements may have arisen, proliferated, and evolved.
相似文献
107.
Distribution of the molossinus allele of Sry, the testis-determining gene, in wild mice 总被引:3,自引:0,他引:3
Nagamine CM; Shiroishi T; Miyashita N; Tsuchiya K; Ikeda H; Takao N; Wu XL; Jin ML; Wang FS; Kryukov AP 《Molecular biology and evolution》1994,11(6):864-874
When the Y chromosome of the laboratory inbred mouse strain C57BL/6 (B6) is
replaced by the Y of certain strains of Mus musculus domesticus, testis
determination fails and all XY fetuses develop either as hermaphrodites or
XY females (XY sex reversal). This suggests the presence of at least two
alleles of Sry, the male-determining gene on the Y:M. m. domesticus and B6.
The B6 Y chromosome is derived from the Japanese house mouse, M. m.
molossinus and therefore carries a molossinus Sry allele. As a first step
to determine how the molossinus Sry allele evolved, its distribution
pattern was determined in wild mice. The cumulative data of 96 M. musculus
samples obtained from 58 geographical locations in Europe, North Africa,
and Asia show the molossinus Sry allele is restricted to Japan and the
neighboring Asian mainland and confirm that Japanese M. m. molossinus mice
were derived in part from a race of M. m. musculus from Korea or Manchuria.
Sry polymorphisms, as illustrated by the molossinus Sry allele, can serve
as molecular markers for studies on the evolution of wild M. musculus
populations and can help determine the role sex determination plays in
speciation.
相似文献
108.
Nikoletta Rovina Andreas Papapetropoulos Androniki Kollintza Makrina Michailidou Davina CM Simoes Charis Roussos Christina Gratziou 《Respiratory research》2007,8(1):53
BackgroundPatients with bronchitis type of chronic obstructive pulmonary disease (COPD) have raised vascular endothelial growth factor (VEGF) levels in induced sputum. This has been associated with the pathogenesis of COPD through apoptotic and oxidative stress mechanisms. Since, chronic airway inflammation is an important pathological feature of COPD mainly initiated by cigarette smoking, aim of this study was to assess smoking as a potential cause of raised airway VEGF levels in bronchitis type COPD and to test the association between VEGF levels in induced sputum and airway inflammation in these patients.Methods14 current smokers with bronchitis type COPD, 17 asymptomatic current smokers with normal spirometry and 16 non-smokers were included in the study. VEGF, IL-8, and TNF-α levels in induced sputum were measured and the correlations between these markers, as well as between VEGF levels and pulmonary function were assessed.ResultsThe median concentrations of VEGF, IL-8, and TNF-α were significantly higher in induced sputum of COPD patients (1,070 pg/ml, 5.6 ng/ml and 50 pg/ml, respectively) compared to nonsmokers (260 pg/ml, 0.73 ng/ml, and 15.4 pg/ml, respectively, p < 0.05) and asymptomatic smokers (421 pg/ml, 1.27 ng/ml, p < 0.05, and 18.6 pg/ml, p > 0.05, respectively). Significant correlations were found between VEGF levels and pack years (r = 0.56, p = 0.046), IL-8 (r = 0.64, p = 0.026) and TNF-α (r = 0.62, p = 0.031) levels both in asymptomatic and COPD smokers (r = 0.66, p = 0.027, r = 0.67, p = 0.023, and r = 0.82, p = 0.002, respectively). No correlation was found between VEGF levels in sputum and pulmonary function parameters.ConclusionVEGF levels are raised in the airways of both asymptomatic and COPD smokers. The close correlation observed between VEGF levels in the airways and markers of airway inflammation in healthy smokers and in smokers with bronchitis type of COPD is suggestive of VEGF as a marker reflecting the inflammatory process that occurs in smoking subjects without alveolar destruction. 相似文献
109.
The phylogenetic position of Rhopalura ophiocomae (Orthonectida) based on 18S ribosomal DNA sequence analysis 总被引:2,自引:0,他引:2
Hanelt B; Van Schyndel D; Adema CM; Lewis LA; Loker ES 《Molecular biology and evolution》1996,13(9):1187-1191
The Orthonectida is a small, poorly known phylum of parasites of marine
invertebrates. Their phylogenetic placement is obscure; they have been
considered to be multicellular protozoans, primitive animals at a
"mesozoan" grade of organization, or secondarily simplified flatworm- like
organisms. The best known species in the phylum, Rhopalura ophiocomae, was
collected on San Juan Island, Wash. and a complete 18S rDNA sequence was
obtained. Using the models of minimum evolution and parsimony, phylogenetic
analyses were undertaken and the results lend support to the following
hypotheses about orthonectids: (1) orthonectids are more closely aligned
with triploblastic metazoan taxa than with the protist or diploblastic
metazoan taxa considered in this analysis; (2) orthonectids are not derived
members of the phylum Platyhelminthes; and (3) orthonectids and rhombozoans
are not each other's closest relatives, thus casting further doubt on the
validity of the phylum Mesozoa previously used to encompass both groups.
相似文献
110.
Smid Eddy J Erkus Oylum Spus Maciej Wolkers-Rooijackers Judith CM Alexeeva Svetlana Kleerebezem Michiel 《Microbial cell factories》2014,13(1):1-9
This review describes the recent advances made in the studies of the microbial community of complex and undefined cheese starter cultures. We report on work related to the composition of the cultures at the level of genetic lineages, on the presence and activity of bacteriophages and on the population dynamics during cheese making and during starter culture propagation. Furthermore, the link between starter composition and starter functionality will be discussed. Finally, recent advances in predictive metabolic modelling of the multi-strain cultures will be discussed in the context of microbe-microbe interactions.
相似文献